Circuit-breaker.



' No. 744,125. PATENTED NOV. I7, 1903.

S. B. STEWART, JR.

CIRCUIT BREAKER.

APPLICATION FILED JAN. 23, 1901.

UNITED STATES Patented November 17, 1903.

PATENT OFFICE.

SAMUEL B. STEWART, JR., OF SCHENECTADY, NEV YORK, ASSIGNOR TO GENERALELECTRIC COMPANY, A CORPORATION OF NEW YORK.

CIRCUIT-BREAKER.

SPECIFICATION forming part of Letters Patent No. 744,125, dated November17, 1903.

Application led January 23,1901. Serial No. 44.342. (No model.)

To all whom, t T12/ty concern:

Be it known that I, SAMUEL B.STEWART,J r. a citizen of the UnitedStates, residing at Schenectady, county of Schenectady, State of NewYork, have invented certain new and useful Improvements inCircuit-Breakers, of which the following is a specification.

rThis invention relates to circuit-breakers for currents of largeamperage and considerable potential, the object being to provide adevice of this character which will be more compact than those hithertomanufactured and which will have all live parts completely inclosed toavoid possibility of shock by contact of operators or others withexposed parts.

The invention is particularly advantageous for use on trolley-cars, itssmall compass and freedom from danger rendering it desirable for thispurpose.

The invention involves mechanical features of construction by which acom-pact organization is provided and by which the operative parts maybe completely housed in a protecting-casing. To these ends I provide twofixed terminals, `in operative relation to which is a movable contactpivoted on the same stud as an operating-lever, the handle of whichprojects outside of the casing. The

movable contact is spring-pressed by a helical spring surrounding thestud on which the arm which carries it is pivoted and coperates with adetent having a sloping shoulder which engages a corresponding shoulderon the supportingarm. This detent lies at right angles to a latch orlock, and the two are connected by a spring normally in a condition ofstress and tending to drop the detent behind the beveled shoulder on thecontact-arm, and also to press the latch over a shoulder on the detent.Secured to the operating-lever is a lug adapted to press back the latchand by a further movement to force the detent out of engagement with thecontact-arm. An electromagnetic trip is arranged to similarly actuatethe latch and detent. The stud, which supports the pivoted contact-arm,forms an integralV part of the core of the blow-out coil, thecover-plate of the casingconstituting an extended pole, and an ironcasting on the bottom forming another pole. Between the poles is ablow-out chute, at the inner end of which are placed thecircuit-terminals.

'The novel features of the invention will be specifically describedhereinafter and delinitely indicated in the claims appended to thisspecification.

In the accompanying drawings, which illustrate the invention, Figure lis a plan view of a circuit-breaker embodying my improvements. Fig. 2 isa sectional elevation on a plane at right angles to that indicated inFig. l. Fig. 3 is a detached view of the operatinglever, handle, andmovable contact. Fig. 4 is a detail view ol' the automatic trippingdevice.

l represents a blow-out coil placed in series relation to the contacts 22, The core of this magnet is secured in a cast-iron plate 3, formingpart of the bottom of the casing, the body of which is formed of abox-like casting provided with openings at the ends to permit themovements of the handle and accommodate the insulating-plates 4. A,which form the top and bottom walls of the blow-outl chute. Thecast-metal cover 5 closes the top of the easing. The movable bridgingcontact 6 is carried on and insulated from an arm 7, pivoted von thestud, which forms a continuation of the core 8 of the blow-out magnet.Around this -stud is a helical spring 9, one end of which is anchored ina cap-plate 10, secured to the stud, and the other end in the hub of thepivoted arm 7. The operating-lever is pivoted on the hub of the arm '7,as indicated at 1l. This operating-lever and the hub are connected by ahelical spring 12, secured to lugs or ears projecting from therespective parts, which spring tends to draw the two parts to a positionwhere cooperating lugs 13 13 engage one another, and thus prevent thehandle fromswinging under vibration or rocking of the car and trippingthe circuitbreaker. Thus when the operating-handle 14. is moveddownwardly and the device occupies the position shown in Fig. 1 the lugs13 13 engage and permit the handle to give a positive movement againstthe tension of spring 9 to the bridging-contact 6, thus forcing thelatter into engagement with the terminal contacts 2 2f and closing thecircuit.

IOO

When set in this position, the beveled detent 15 drops behind thesloping wall 16, projecting from the movable contact, and at the sametime a latch 17, projecting through a hole in the detent, drops over theend wall of the hole under the tension of a spring 18 and positivelylocks the detent in engagement with the lug 16 on the movable contact.The detent is carried on a lever pivoted on the side of the casing andstands at right angles to the latch 17, the latter having an elbow 17,in which the end of the helical spring is connected. Thus the twolevers, the detent, and the latch are always drawn toward a lockingposition by the spring 1S, so that immediately on the bridging-contactbeing shifted to the positionwhere the beveled nose of the detent candrop behind the shoulder 16 the latch 17 falls into place and locks itin that position, where it remains until forced away by the releasing'devices. These releasing devices are twofold in character, one beinghand-operated and comprising a lug 19, forming a part of the handoperating-lever, which after a determinate range of motion of the handlepresses against the latch 17 and raises it from engagement with the wallof the detent. Then the parts are well lubricated, this will besufficient to effect an opening of the circuit; but to make such openingmovement perfectly certain I provide an auxiliary lug, (indicated indotted lines in Fig. 2 at19,) which upon further traverse after the lug19 has acted forces the detent 15 outwardly and effects a positivedisengagement of the coperating beveled shoulders.

The automatic releasing` device comprises an armature 20, pivoted on thecover in a plane to be in proximate relation to the extension of thecore S of the blow-out magnet. Rigidly connected with the armature is atongue 21, crossing the plane of the latch and detent at a point withinthe range of both of them, as indicated in Fig. 1, whereby when thearmature is drawn up to the pole of the magnet the tongue 21 iirst ridesover the inclined shoulder 21 on the latch, thus opening it, and thenengages the detent, effecting a positive release in a fashion similartothat already described in connection with the hand-operated releasingdevice.

The iixed circuit-terminals 2 2 are at the inner end of a blow-outchute, across which a magnetic field is maintained by the iron cover 5and the casting 3, which form poles of the blow-out magnet. This chutemay be made of any suitable insulating material, such as liber, and iscomposed of top and bottom walls fi at and side walls 22 22, doweled orotherwise secured to the plates. At the innerend of the chute and in thepath of the gases expelled from the arc when the circuit is being brokenare arcing contacts 23 23, formed of copper or other metal, whichprevent serious burning of the circuit-breaker contacts. These contactsare fastened in place by bolts, as indicated in Fig. l, so as to beexchangeable when damaged. Being in contact with the circuitterminals,when a conductive path is formed between them by the expulsion of thearc gases, the potential at the contacts is red need, the final openingof the circuit being effected by rupture of the arc-stream at thecontacts 23. ln order to effect a better contact, one of the terminalsmay be provided with an auxiliary contact 24, formed of a bundle oflamina; of phosphor-bronze or other good conductor, screwed fast to theone terminal in a position to be engaged by the bridging-contact 6 whenthe circuit is closed.

The armature of the magnetic releasing device is controlled by a helicalspring 25, attached to a lug 27 on the tongue 21 of the armature, thetension of which may be varied by adjusting screw 26 in a manner wellunderstood in the art and by which the exact point of current strengthat which the circuit is to open may be determined.

All parts of the casing are insulated from the circuit-termin als or anylive parts of the circuit-breaker, and all parts carrying current arecompletely housed within the casing, a construction of great advantagein a circuitbreaker designed for use on trolley-cars or other placeswhere the pressure of a crowd renders contact of people with the devicepossible.

In setting the circuit-lneaker a movement of the handle 14(downwardly inthe drawings) brings the lug 13, forming a part of the operating-leveragainst the lug 13 and carries the movable contact-arm 7 around againstth e tension of its operating-spring until the detent 15 engages withthe shoulder 16, the latch 17 locking the parts in position. lf itbecomes desirable for any reason for the motorman to open the circuit byhand, the handle may be moved, (upwardly in the drawings,) therebyshifting the lug 19 and opening the latch and then bringing the lug 19against the detent and disengaging it, permitting the energy stored inthe spring 9 to throw the bridgingcontact 6 rapidly away from thecontact 2 with a snapping action, drawing an arc which is instantlyruptured by the magnetic field inclosing the contacts. Thebridging-contact when tripped has independent motion suiiicient in rangeto safely open the circuit whether the operator holds the handle or not.

In case of an overload on the circuit in which the circuit-breaker isconnected the armature 2O is drawn down against the tension of spring 25and brin the arm 2l. against the inclined shoulder on the latch, therebyraising the latter and then forcing outwardly the detent, thus releasingthe movable contact and permitting the circuit to open, as abovedescribed.

W'hat l claim as new, and desire to secure by Letters Patent of theUnit-ed States, is-

1. A circuit-breaker comprising fixed and movable contacts, anoperating-lever, the

movable contact and operating-lever being independentlT pivoted at thesame point, a spring independent of the operating-lever governing themovable contact and adapted to be strained bysaid lever, and a detentfor the spring adapted to be released by the lever, the lever andmovable contact having sufficient lost motion to open the circuitindependently of the lever motion when the do tent is released.

2. A circuit-breaker comprising two fixed contacts, a movable bridgingcontact, an arm carrying the same from which it is insulated, anoperating-lever, both arm and lever being' pivoted on the same stud, aspring independent of the operating-lever surrounding the stud andcontrolling the contact-arm, a detent for locking the arm in a closedposition,

lock the movable contact when it reaches a closed position.

4. A circuit-breaker comprising a springactuated contact, anoperating-handle for compressing the spring, a detent for holding thecircuit closed, a latch 'for locking the detent, a tripping-lug carriedby the operatinglever ifor opening the latch, and an auxiliary lug'fordisengaging the detent.

5. A circuit-breaker comprising a springactuated contact, an operatinghandle for compressing the spring, a detent for holding the circuitclosed, provided with a beveled engaging tip, a latch for locking thedetent, and two tripping-lugs on the operating-lever operating insequence, one to trip the latch and the other the detent.

G. A circuit-breaker comprising a blow-ont magnet, a movable contact andoperatinglever j ournaled on an axis in prolongation of the magnet-core,a controlling-spring, detent and releasing devices for tripping thecircuitbreaker.

In witness whereof l have hereunto set my hand this 21st day of January,190i.

SAMUEL B. STEWART, JR.

X'Vitnesses:

BENJAMIN B. HULL, MABLE H. EnEnsoN.

